Known glazing panels comprise two or more panes of glass spaced apart a short distance and the gap between them sealed peripherally either by a spacer or the frame of the window, patio door, or other opening in which it is installed.
In use, such a glazing panel may develop one or more leaks in the peripheral seal, allowing moist air and/or other contamination to enter the air space. In other cases, vent holes provided to avoid excessive pressure/vacuum build up as the glazing panel is heated or cooled may admit such moist air and/or contamination. Under certain conditions, moisture may condense out of the air within the air space and form condensation on the inner surface of at least one of the panes. This reduces visibility through the panel. Even if the glazing panel warms up and the moisture evaporates, it may leave a deposit of minerals, for example, on the pane, again reducing visibility. Moreover, it is also possible for other forms of contamination, such as particulate matter, to be drawn into the air space as the panel cools and a partial vacuum is created within it.
A method of removing and/or preventing condensation and contaminant buildup in glazing panels is described in Canadian patent No. 1,332,541, to which the reader is directed to for reference. The method involves forming at least one hole in the external pane, removing condensation and/or contamination from the air space, and then attaching a filter means in the form of a patch to close the hole. The filter contains interstices sized to allow moisture to be expelled from the panel as the window heats, but restrict ingress of water droplets as air is drawn back into the panel as it cools.
This method is not entirely satisfactory, however, but has certain limitations and disadvantages, at least for some applications.
The present invention seeks to eliminate, or at least mitigate, the limitations and disadvantages of such known method, or at least provide an alternative.
One specific disadvantage of such known method is that it may be difficult to gain access to the outside of the glazing panel, perhaps because it is installed in a high-rise building.
Embodiments of a first aspect of the present invention address this disadvantage by drilling the hole in the external pane of a glazing panel via a generally aligned hole in the interior pane.
Thus, according to this first aspect of the present invention there is provided a method of treating a glazing panel to remove contamination from and/or inhibit ingress of contamination into an enclosed air space of the glazing panel, the glazing panel comprising at least an exterior pane and an interior pane and spacing and sealing means extending around and sealing the perimeters of the panes to form said enclosed air space therebetween, said method comprising the steps of:
(i) creating an access hole in the interior pane from its surface furthest from the exterior pane, said access hole communicating with the air space;
(ii) through the access hole, creating a vent hole in the exterior pane through which hole the air space communicates with ambient air;
(iii) applying a filter means to the vent hole to filter air passing therethrough; and
(iv) sealing the access hole,
wherein the vent hole is located at a position lower than that of the access hole.
Another disadvantage of such known method is that it cannot readily be applied where the glazing panel comprises tempered glass panes, such as are used in patio doors, since drilling a hole in such a pane may cause the glass to shatter.
Embodiments of the present invention address this disadvantage by dispensing with drilling holes through the panes, and instead drilling the required hole or holes through the frame so that the air space communicates with the ambient through the frame supporting the panes. Thus, such embodiments provide a method of treating a sealed glazing unit installed into a surrounding frame and comprising at least an exterior pane and an interior pane, and spacing and sealing means extending around and sealing the perimeters of the panes to provide an air space therebetween, the frame having a side face adjacent each pane and an edge surface generally perpendicular to the panes and directed outwardly therefrom, the method comprising the steps of:
(i) drilling at least one vent hole from an external face of the frame of the installed glazing unit for providing air flow communication through the frame and between the air space and ambient, and
(ii) applying a filter means to the vent hole to filter air passing between the air space and ambient.
Thus, employing a method according to embodiments of the invention results in a sealed glazing unit comprising at least an exterior pane and an interior pane, spacing and sealing means extending around and sealing the perimeters of the panes to provide an enclosed air space therebetween and a frame surrounding the glazing unit, the frame having a side region adjacent the means extending around and sealing the perimeters of the panes and an outer region, venting means for providing air flow communication between the air space and ambient air, said venting means being formed within the frame surrounding the glazing unit; and filter means attached to a region of the venting means for filtering air passing between the air space and ambient said filter means comprising means for permitting the egress of moisture-laden air from the air space when the air space temperature and pressure are elevated relative to ambient and inhibiting the ingress of moisture droplets from ambient air when the temperature and pressure of the air in the air space are less than ambient.
Where this entails drilling through a compartment containing desiccant, the desiccant may be lost through the drilled hole. Likewise, where the frame comprises an extrusion with compartments defined by structural webs and flanges, the buildup of moist air between the air space and ambient may occur.
Methods embodying the invention may provide a sealed glazing unit comprising at least an exterior pane and an interior pane, spacer means supporting the perimeters of the panes to provide an enclosed air space therebetween and a frame surrounding the glazing unit, the frame having a side face adjacent each pane and an edge surface perpendicular to the panes and directed outwardly therefrom, and venting means comprising a passageway extending through the frame to provide air flow communication between the air space and ambient air and a filter for filtering air passing through the passageway between the air space and ambient, said passageway comprising a tubular insert extending at least partially through the spacer means.
Methods embodying the present invention may provide, a sealed glazing unit comprising at least an exterior pane and an interior pane, spacer means supporting the perimeters of the panes to provide an enclosed air space therebetween and a frame surrounding the glazing unit, the frame having an interior flange and an exterior flange extending across and engaging respective margin portions of the outmost surfaces of the interior and exterior panes, respectively, said interior and exterior flanges being integral with the frame, venting means extending through the frame for providing air flow communication between the air space and ambient air; and filter means for filtering air passing through the venting means between the air space and ambient, said filter means comprising means for permitting the egress of moisture-laden air from the air space when the air space temperature and pressure are elevated relative to ambient and inhibiting the ingress of moisture droplets from ambient air when the temperature and pressure of the air in the air space are less than ambient.
Yet another disadvantage is that there is a trade-off between hole size and filter size. Thus, it is desirable to keep the diameter of the hole small so as to make it quicker and easier to drill and reduce the risk of breakage, but it is desirable for the open area of the filter, i.e., the aggregate area of the interstices, to be as great as possible so as to reduce resistance to air flow.
Thus, in embodiments of a sixth aspect of the present invention, there is provided a filter having a surface area greater than the planar area bounded by its perimeter.
Filter means for use with methods of the present invention when treating a glazing panel comprising at least an exterior pane and an interior pane and means extending around and sealing the perimeters of the panes to provide an internal air space therebetween, one of the interior or exterior panes having a hole, may comprise a marginal region for attaching the filter to said hole and a medial region comprising a membranous filter screen having interstices sized to permit the egress of moisture-laden air from the panel when its interior temperature and pressure are elevated relative to ambient and to inhibit ingress of moisture droplets with ambient air when the interior temperature and pressure of the air in the air space are greater than ambient, said membranous filter screen being non-planar so that its surface area is greater than its plan area.
Preferably, the filter is non-planar, conveniently dome-shaped, corrugated, or of other non-planar form, so that its surface area is increased as compared with a flat filter of the same perimeter.
It may also be disadvantageous to have a filter patch that is applied to the outside surface of the exterior pane, i.e., so that its margin overlies the exterior surface around the hole, since, even though the patch may protrude only slightly from the surface of the glass, it could impede the cleaning of the panel and generally can only be applied from the exterior of the panel. Moreover, such a patch may be unsightly.
These limitations may be addressed by means of a filter that is supported within the interior of the hole and preferably does not protrude from the surface of the pane.
Thus, methods embodying the present invention may employ filter means comprising a filter screen at least peripheral regions of which are resilient so that, upon insertion of the filter into a hole slightly smaller than the filter, the peripheral regions of the filter engage an interior of the hole to retain the filter therein.
Conveniently, the filter may be slightly larger than the hole and resilient so that it can be compressed to fit into the hole and its peripheral regions grip the interior of the hole. The filter may be dome-shaped and/or have at least its margins corrugated or crimped.
Alternatively, the filter may take the form of a patch applied to the interior surface of the exterior pane so that its margin portion overlies the glass surrounding the hole in the exterior pane.
Hence, the filter means may be installed by passing the filter means through the first hole, and adhering the filter to the interior surface of the exterior pane surrounding the second hole so that the filter covers the internal mouth of the hole.
Preferably, the filter is of magnetic material and a probe having a magnetic tip is used to install it, the filter being attached to the magnetic tip of the probe which is then inserted through the first hole and pressed into position until it adheres to the material surrounding the hole in the exterior pane. The probe then is withdrawn, the adhesion being sufficient to detach the filter from the magnetic tip. The filter may be adhered by means of a contact adhesive applied to its margins. Alternatively, adhesive may be applied to the interior surface, conveniently by means of a suitable probe, before the filter is pressed into place.
The filter may then comprise a flat filter or a dome-shaped filter with the dome protruding towards the interior pane. In either case, the filter may comprise a medial filter membrane supported by a surrounding annular part that adheres to the pane. The annular part may be integral with the membrane or a washer of a different material, e.g. vinyl, attached to the membrane.
The filter may take the form of a perforated membrane as disclosed in the above-mentioned Canadian patent No. 1,332,541. Alternatively, and especially where the filter is in the form of a patch, the filter portion itself may comprise at least one very thin slit in the patch, the width of the slit being small enough to limit ingress of moisture droplets and/or other contamination, the length of the slit being sufficient to provide the required open area.
Thus, a method embodying the present invention, for treating a glazing panel comprising at least an exterior pane and an interior pane and means supporting the perimeters of the panes to provide an internal air space therebetween, either of the panes having a through hole, said may employ filter means being adapted to attach to either of the panes and filter air passing through said hole, said filter means comprising a patch having one or more thin slits therein, the width of the one or more slits being narrow enough to limit ingress of moisture droplets from ambient air when the temperature and pressure of the air in the air space are less than ambient and wide enough to permit the egress of moisture-laden air from the air space when the air space temperature and pressure are elevated relative to ambient and the overall length of the one or more slits being determined so as to provide a required open area for the filter.
Preferably, the slit is non-linear.
The patch may have a central dome surrounded by a substantially flat annular portion, the slit extending, parallel to the flat annular portion, around a part of the base of the dome. Preferably, when such a patch is installed on the exterior of the external pane, the slit is directed downwards to that it is protected by the dome against ingress of rainwater.
Another disadvantage of known, window panels is they are susceptible to damage from pressure changes, which is a problem encountered in certain environments.
Embodiments of tenth aspect of the present invention address this limitation by providing a method of treating a glazing panel by drilling a hole in the exterior pane of a glazing panel via a generally aligned hole in the interior pane.
According to yet another aspect of the present invention, there is provided a method of treating a sealed glazing unit installed into a surrounding frame and comprising at least an exterior pane and an interior pane and spacing and sealing means extending around and sealing the perimeters of the panes to provide an air space therebetween, the frame having a side face adjacent each pane and an edge surface generally perpendicular to the panes and directed outwardly therefrom, the method comprising the steps of:
(i) creating a vent hole having a first portion and a second portion, the first portion of the vent hole extending through the frame from said edge surface and through the spacing and sealing means, said first portion of the vent hole communicating at one end with the air space, and the second portion of the vent hole extending from said side face of the frame to communicate with the first portion of the vent hole, such that the vent hole provides air flow communication through the frame and between the air space and ambient;(ii) installing a filter means to close the second portion of the vent hole and filter air passing between the air space and ambient; and(iii) sealing the first portion of the vent hole exteriorly of the position at which it communicates with the second portion of the vent hole.